Epoxyketone derivatives represented by the structural formulae (1a) and (1b) (wherein PG is a protective group, Boc is a t-butyloxycarbonyl group and Cbz is a benzyloxycarbonyl group, and hereinafter, the same applies in this specification) are important compounds as raw materials for medicines, etc. (Non-patent Document 1 and Patent Document 3). Heretofore, as methods for their production, a production method of directly epoxidizing an α,β-unsaturated ketone (2a) (Non-patent Document 1) and a synthetic method of epoxidizing an allyl alcohol (3a) or (3b) obtainable by reducing an α,β-unsaturated ketone (2a) or (2b), followed by oxidation of an epoxy alcohol (4a) or (4b) (Patent Documents 1, 2 and 3), have been known.
